Image Sharpness

Gabrielle asks,

I always thought my pictures were pretty sharp, well up until I saw some pictures from other photographers. My photos all of a sudden don’t look so sharp anymore. What does a really sharp picture really look like? And I mean without Photoshop edits. I know I’ll end up editing in Photoshop, but I really would love to know what I am capable without edits.

Image sharpness is a very common issue among digital photographers. 

First, it’s important to get one thing straight: Sharpness is a matter of taste.  For some subjects, razor sharp images are great. For others, soft works, and since long before digital cameras photographers have used a variety of filters and other techniques to soften images.

A number of things impact sharpness in digital images:

Motion – If your subject or camera is moving, you’re going to get blurry or sharp images.  Unless you are trying for a motion effect, use a fast shutter speed for sharp images.

Lens – Some lenses are sharper than others, and lenses are sharper at some apertures than at others.  You may want to experiment with your lens to understand its characteristics.

Depth of field – Large apertures and long focal lengths generally result in a short depth of field.  When evaluating sharpness, make sure you’re really looking at sharpness and not depth of field.  If part of the image is sharp and part isn’t, sharpness isn’t the issue.

Camera – Converting an analog image into digital form always results in a loss of sharpness.  In other words, all digital images require sharpening, and digital cameras have a "sharpening" function built-in.  Some cameras allow the user to select the level of sharpening, while others don’t.  In most cases, the manufacturer’s default setting is your best bet.

Jpeg Compression – JPEG uses lossy compression.  When the image is compressed and uncompressed, some loss of detail, and therefore sharpness, occurs.  More advanced cameras offer a "raw" mode, and this generally provides sharper images.  Other cameras allow selection of JPEG quality.  The higher the quality you select, the lower the level of compression, and therefore the sharper the resulting image.  If you are shooting JPEGS, choose the highest quality JPEG your camera offers.  You’ll also want to avoid editing and re-editing jpegs.  Only save an image as a JPEG as the final stage of editing — consider it an output format, but save your edited images as .tif, .psd, or other non-lossy format.

Sharpening – Even if you shoot RAW images and use your camera’s default sharpening, chances are that you’ll still need to sharpen images for printing and before saving them as a jpeg for the web.  In Photoshop I use "Unsharp Mask" to sharpen images as the last step before printing or saving as a jpeg.  If you are resizing images, keep in mind that you’ll want to sharpen them after resizing.  It also helps to view images as close to 100% size as possible to judge the impact of the sharpening.  For images from my Nikon D100, I would often use unsharp mask at 120%, radius 1.2, threshold 1 as a starting point.  For images from my D200, I’ve noticed that I require a significantly lower percentage.

So, in a nutshell, you just might need to sharpen your images like everyone else 🙂

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